Molding of a tire requires an elevated temperature as is well known. Because of this elevated temperature and the large size of a tire and the required tire mold, considerable heat is given off. In the absence of any shielding, this heat would be dissipated in the surrounding atmosphere, i.e., the building in which the tire mold or molds are located. This heat loss is costly.
Heat transfer from a tire mold takes place according to three widely recognized methods, i.e., radiation, convection and conduction. Radiation from a hot tire and a hot tire mold or press to the surroundings accounts for part of the heat transfer. Heat transfer may also take place by convection, i.e, by hot air currents which flow outwards from the vicinity of a hot tire and the tire mold to the surrounding atmosphere. Finally, some heat transfer by conduction will take place. As is well known, metals are good conductors of heat while air is a poor conductor so that heat transfer by conduction takes place mainly from the tire to the tire mold and within the tire mold. From the tire mold outward into the atmosphere, radiation and convection are more important.
It is customary to provide a tire press with an insulated heat shield in order to reduce the amount of heat transferred from the tire mold to the surroundings. Nevertheless, some heat transfer by each of the three above methods will take place.